Nickel-containing high-toughness controllably degradable magnesium alloy material, preparation method therefor and use thereof

ABSTRACT

The present disclosure provides a nickel-containing high-toughness controllably degradable magnesium alloy material, a preparation method therefor and use thereof, and relates to the technical field of magnesium alloys. The magnesium alloy material comprises the following components in percentage by mass: 0.3 to 8.5% of Ni, 0.5 to 28% of RE, with the balance being Mg and unavoidable impurities. RE represents rare earth elements. By adding Ni and RE elements to introduce an Mg12RENi-type long-period phase, an Mg2Ni phase and an MgxREy phase, the magnesium alloy material provided by the present disclosure significantly improves mechanical properties of the alloy material, the tensile strength being up to 510 MPa. At the same time, the presence of the Mg12RENi-type long-period phase and Mg2Ni phase enables the alloy material to be controllably degradable, and enables the degradation rate to be adjustable between 360 and 2400 mm/a. Downhole fracturing tools manufactured by using the magnesium alloy alleviates the technical problem existing in current downhole tools and satisfy the requirements in the field of oil and gas exploitation.

CROSS-REFERENCE TO RELATED APPLICATION

The present disclosure claims priority of Chinese patent applicationwith the filing number 201811237934.1 filed on Oct. 23, 2018 with theChinese Patent Office, and entitled “Nickel-containing High-toughnessControllably Degradable Magnesium Alloy Material, Preparation Methodtherefor and Use thereof”, the contents of which are incorporated hereinby reference in entirety.

TECHNICAL FIELD

The present disclosure relates to the technical field of magnesiumalloy, in particular to a nickel-containing, high-strength andhigh-toughness, controllably degradable magnesium alloy material, apreparation method therefor and use thereof.

BACKGROUND ART

With the rapid progress of economy, the petroleum problem in China hasbecome one of the important problems with national concern. According tostatistical data of the national statistical bureau, the net petroleumimport in China is increasing continuously, and the dependency ofpetroleum in China on foreign countries directly breaks through 60% by2015. According to international experience and opinion of people inauthority, the dependency of petroleum in China on foreign countriesmust be kept below 60%. China should reduce the dependency of petroleumon foreign countries, both from a strategic point of view and due toconcerns about national safety and normal economic operation. Therefore,increasing the mining power of internal petroleum and improving thepetroleum mining efficiency is an important measure for buildingpowerful China, and it is urgent to explore new technologies andresearch and develop new materials.

China has abundant low-permeability oil and gas resources, and possessesgreat exploration and exploitation potential. The stable production andyield increase of future oil and gas production will depend onunconventional low-permeability oil and gas resources to a great extent.However, most of these unconventional oil and gas resources aredistributed in strata with different depths, and the single-wellproductivity needs to be improved by simultaneously transforming aplurality of strata by adopting a multi-layer and multi-sectionfracturing technology, so that the yield of oil field and theconstruction efficiency are improved.

In multi-layer and multi-section fracturing, a packing tool (such asfracturing ball and bridge plug) needs to be used between layers andsections, so as to, after separation, carry out fracturingtransformation layer by layer, and after the construction of all layersand all sections is completed, the packing tool is cleaned up from awellbore, so as to break through a well and realize exploitation of oiland gas. However, most of the existing common packing tools are made ofsteel, and have the defects of difficult drilling and milling, long-timeconsumption, difficult removal of powders and fragments after drillingand so on, which greatly increases the construction period and cost.

Therefore, a light-weight fracturing ball capable of bearing a highpressure of fracturing construction and a high temperature of an oilwell, and controllably and rapidly being corroded in the fluidenvironment of the oil well is researched, so that the construction costand risk can be effectively reduced, the construction period can beshortened, and the construction efficiency can be improved.

SUMMARY OF THE INVENTION

Object of the present disclosure include, for example, providing anickel-containing, high-strength and high-toughness, controllablydegradable magnesium alloy material, so as to solve the technicalproblems that most of the existing common packing tools, made of steel,have the defects of difficult drilling and milling, long timeconsumption, difficult removal of powders and fragments after drillingand so on, which greatly increases the construction period and the cost.

The nickel-containing, high-strength and high-toughness, controllablydegradable magnesium alloy material provided in the present disclosureincludes following components in percentage by mass: 0.3˜8.5% of Ni,0.5˜28% of RE, and the balance of Mg and unavoidable impurities, whereinRE is a rare earth element, and Mg, Ni and RE form an Mg₁₂RENi-typelong-period stacking ordered phase (i.e., Mg₁₂NiRE-type long-periodstacking ordered phase), an Mg₂Ni phase and an Mg_(x)RE_(y) phase,wherein a volume fraction of the Mg₁₂RENi-type long-period stackingordered phase is 3˜70%, a volume fraction of the Mg₂Ni phase is 0.5˜10%,a volume fraction of the Mg_(x)RE_(y) phase is 0.5˜22%, and a valuerange of x:y is (3˜12):1.

In one or more embodiments, the nickel-containing, high-strength andhigh-toughness, controllably degradable magnesium alloy materialincludes following components in percentage by mass: 0.5˜8.0% of Ni,1.5˜20% of RE, and the balance of Mg and unavoidable impurities.

In one or more embodiments, the nickel-containing, high-strength andhigh-toughness, controllably degradable magnesium alloy materialincludes as-cast magnesium alloy, as-extruded magnesium alloy and agedmagnesium alloy.

In one or more embodiments, the as-cast magnesium alloy includes anMg₁₂NiRE-type long-period stacking ordered phase, an Mg₅RE phase and anMg₂Ni phase, wherein a volume fraction of the Mg₁₂NiRE-type long-periodstacking ordered phase is 3˜65%, a volume fraction of the Mg₂Ni phase is0.5˜6%, and a volume fraction of the Mg₅RE phase is 0.5˜15%.

In one or more embodiments, the as-extruded magnesium alloy includes anMg₁₂NiRE-type long-period stacking ordered phase, an Mg₂Ni phase and anMg₅RE phase, wherein a volume fraction of the Mg₁₂NiRE-type long-periodstacking ordered phase is 4˜70%, a volume fraction of the Mg₂Ni phase is1%˜8%, and a volume fraction of the Mg₅RE phase is 1˜20%.

In one or more embodiments, the aged magnesium alloy includes anMg₁₂NiRE-type long-period stacking ordered phase, an Mg₂Ni phase and anMg_(x)RE_(y) phase, wherein a volume fraction of the Mg₁₂NiRE-typelong-period stacking ordered phase is 4˜70%, a volume fraction of theMg₂Ni phase is 2˜10%, and a volume fraction of the Mg_(x)RE_(y) phase is2˜22%, wherein a value range of x:y is 3:1˜12:1.

In one or more embodiments, the RE is at least one selected from thegroup consisting of Gd, Y, Er, Dy, Ce and Sc.

In one or more embodiments, the nickel-containing, high-strength andhigh-toughness, controllably degradable magnesium alloy materialincludes following components in percentage by mass: 0.3˜8.5% of Ni,0.5˜28% of RE, 0.03˜10% of M, and the balance of Mg and unavoidableimpurities, wherein M is an element capable of alloying with magnesium.

In one or more embodiments, the content of the unavoidable impurities,in percentage by mass, is not higher than 0.2% in the magnesium alloymaterial.

In one or more embodiments, M is at least one of Fe, Cu and Mn.

Object of the present disclosure include, for example, providing amethod for preparing a nickel-containing, high-strength andhigh-toughness, controllably degradable magnesium alloy material,including the following step: uniformly mixing a nickel source, amagnesium source and a rare earth source, and carrying out alloyingtreatment to obtain the nickel-containing, high-strength andhigh-toughness, controllably degradable magnesium alloy material.

In one or more embodiments, the nickel source is selected from elementalnickel and/or nickel alloy.

In one or more embodiments, the nickel alloy is at least one selectedfrom the group consisting of magnesium-nickel alloy, nickel-yttriumalloy and zinc-nickel alloy.

In one or more embodiments, the magnesium source is selected fromelemental magnesium and/or magnesium alloy.

In one or more embodiments, the magnesium alloy is at least one selectedfrom the group consisting of magnesium-gadolinium alloy,magnesium-yttrium alloy, magnesium-zinc alloy, magnesium-nickel alloy,magnesium-calcium alloy and magnesium-iron alloy.

In one or more embodiments, the rare earth source includes elementalrare earth and/or rare earth intermediate alloy.

In one or more embodiments, the elemental rare earth includes at leastone selected from the group consisting of gadolinium, yttrium, erbium,dysprosium, cerium and scandium.

In one or more embodiments, the rare earth intermediate alloy includesat least one selected from the group consisting of magnesium-gadoliniumalloy, magnesium-yttrium alloy, magnesium-erbium alloy, magnesium-ceriumalloy, magnesium-scandium alloy, nickel-yttrium alloy, nickel-gadoliniumalloy, nickel-erbium alloy, nickel-cerium alloy and nickel-scandiumalloy.

In one or more embodiments, the alloying treatment includes a smeltingand casting method and a powder alloying method.

In one or more embodiments, the alloying treatment is carried out byadopting the smelting and casting method.

In one or more embodiments, the smelting and casting method includesfollowing steps:

(a) casting: uniformly mixing a nickel source, a magnesium source and arare earth source, and carrying out smelting and casting to obtain amagnesium alloy ingot; and

(b) heat treatment: carrying out, in sequence, homogenization treatmentand extrusion heat deformation treatment on the magnesium alloy ingot,to obtain the nickel-containing, high-strength and high-toughness,controllably degradable magnesium alloy material.

In one or more embodiments, the step (b) also includes an aging heattreatment step, wherein the aging heat treatment step is carried outafter the extrusion heat deformation treatment.

In one or more embodiments, in the step (a), when the smelting andcasting is carried out, the temperature is first increased to 690˜800°C. and maintained, the raw materials are stirred to enable them to meltcompletely, then the temperature is reduced to 630˜680° C. andmaintained for 20˜120 min, and after cooling, the magnesium alloy ingotis obtained.

In one or more embodiments, an inert gas is used during the smelting andcasting for protection.

In one or more embodiments, the inert gas is at least one selected fromthe group consisting of helium, argon, carbon dioxide and sulfurhexafluoride, for example, argon. In one or more embodiments, a coolingmethod is at least one selected from the group consisting of brine bath,water quenching, furnace cooling and air cooling.

In one or more embodiments, smelting is carried out using a resistancefurnace or a line frequency induction furnace.

In one or more embodiments, in the step (a), the nickel source, the rareearth source and the magnesium source are accurately weighed accordingto formula requirements, and uniformly mixed.

In one or more embodiments, in the step (b), the homogenizationtreatment is carried out at a temperature of 400˜550° C. for 4˜40 h.

In one or more embodiments, in the step (b), an extrusion ratio in theextrusion heat deformation treatment is 8˜40.

In one or more embodiments, the extrusion heat deformation treatment iscarried out at a temperature of 360˜480° C.

In one or more embodiments, in the step (b), the aging heat treatment iscarried out at a temperature of 150˜250° C. for 12˜120 h.

In one or more embodiments, in the step (b), the aging heat treatment iscarried out at a temperature of 180˜220° C. for 15˜60 h.

Object of the present disclosure include, for example, providing use ofa nickel-containing, high-strength and high-toughness, controllablydegradable magnesium alloy material in the field of oil and gasexploitation.

The present disclosure at least has following beneficial effects:

(1) The nickel-containing, high-strength and high-toughness,controllably degradable magnesium alloy material provided in the presentdisclosure takes magnesium as a base material, and the Mg₁₂RENi-typelong-period stacking ordered phase, the Mg₂Ni phase and the Mg_(x)RE_(y)phase are formed by adding Ni and RE, so that the tensile strength andplasticity of the alloy material are remarkably improved; meanwhile, aquite large electronegativity difference exists between theMg₁₂RENi-type long-period stacking ordered phase and the Mg₂Ni phase,and the magnesium matrix, and a large number of micro-batteries areformed, so that the generated nickel-containing, high-strength andhigh-toughness, controllably degradable magnesium alloy material can berapidly decomposed, and the downhole fracturing tool made of thismagnesium alloy material can effectively meet the requirements of thefield of oil and gas exploitation.

(2) When applied to the field of oil and gas exploitation, thecontrollably degradable alloy material provided in the presentdisclosure can be degraded completely downhole after accomplishing atask, and discharged through a pipe-line, without problems of easyblocking or jam, thus leaving out the drilling and grinding recyclingprocess, reducing the engineering degree of difficulty, and improvingthe construction efficiency.

DETAILED DESCRIPTION OF EMBODIMENTS

Embodiments of the present disclosure will be described in detail belowin combination with examples, while a person skilled in the art wouldunderstand that the following examples are merely used for illustratingthe present disclosure, but should not be considered as limitation onthe scope of the present disclosure. If no specific conditions arespecified in the examples, they are carried out under normal conditionsor conditions recommended by manufacturers. If manufacturers of reagentsor apparatuses used are not specified, they are all conventionalproducts commercially available.

According to one aspect of the present disclosure, the presentdisclosure provides a nickel-containing, high-strength andhigh-toughness, controllably degradable magnesium alloy material,including following components in percentage by mass: 0.3˜8.5% of Ni,0.5˜28% of RE, and the balance of Mg and unavoidable impurities, whereinRE is a rare earth element, and Mg, Ni and RE mainly form anMg₁₂RENi-type long-period stacking ordered phase, an Mg₂Ni phase and anMg_(x)RE_(y) phase.

A volume fraction of the Mg₁₂RENi-type long-period stacking orderedphase is 3˜70%, a volume fraction of the Mg₂Ni phase is 0.5˜10%, and avolume fraction of the Mg_(x)RE_(y) phase is 0.5˜22%.

In one or more embodiments, the content of the unavoidable impurities inthe magnesium alloy material, in percentage by mass, is not higher than0.2%.

In one or more embodiments, the long-period stacking ordered phase(LPSO), a new reinforcing phase in magnesium alloy, is formed byperiodic changes in atomic position or chemical composition in a crystalstructure, and the long-period structure is divided into two aspects,namely, stacking order and chemical composition order, and theMg₁₂RENi-type long-period stacking ordered phase in one or moreembodiments is a result of combined effect of both stacking order andchemical composition order.

In the nickel-containing, high-strength and high-toughness, controllablydegradable magnesium alloy material provided in the present disclosure,a typical but non-limited content of Ni (nickel), in percentage by mass,is, for example, 0.3%, 0.5%, 0.8%, 1%, 1.2%, 1.5%, 1.8%, 2%, 2.2%, 2.5%,2.8%, 3%, 3.2%, 3.5%, 4%, 4.2%, 4.5%, 4.8%, 5%, 5.5%, 6%, 6.5%, 7%,7.5%, 8% or 8.5%.

In the nickel-containing, high-strength and high-toughness, controllablydegradable magnesium alloy material provided in the present disclosure,a typical but non-limited content of RE, in percentage by mass, is, forexample, 0.5%, 1%, 2%, 3%, 4%, 5%, 8%, 10%, 12%, 15%, 18%, 20%, 22%, 25%or 28%.

In one or more embodiments, the volume fraction of the Mg₁₂RENi-typelong-period stacking ordered phase is 3˜70%, the volume fraction of theMg₅RE phase is 0.5˜20%, the volume fraction of the Mg₂Ni phase is0.5˜10%, the volume fraction of the Mg_(x)RE_(y) phase is 0.5˜22%, and avalue range of x:y is (3˜12):1 (i.e., 3:1˜12:1).

By setting the volume fraction of the Mg₁₂RENi-type long-period stackingordered phase to be 3˜70%, the volume fraction of the Mg₂Ni phase to be0.5˜10%, and the volume fraction of the Mg_(x)RE_(y) phase to be0.5˜22%, the Mg₁₂RENi-type long-period stacking ordered phase and theMg_(x)RE_(y) phase remarkably improve the tensile strength of the alloymaterial, and enable the alloy to maintain certain plasticity; andmeanwhile, a relatively large potential difference exists between theMg₁₂RENi-type long-period stacking ordered phase and the Mg₂Ni phase,and the magnesium matrix, and a large number of micro-batteries areformed, so that the generated alloy material can be rapidly decomposed,which effectively meets the requirements of the field of oil and gasexploitation on downhole tool materials.

In one or more embodiments, in the nickel-containing, high-strength andhigh-toughness, controllably degradable magnesium alloy material, atypical but non-limited volume fraction of the Mg₁₂RENi-type long-periodstacking ordered phase is, for example, 3%, 4%, 5%, 8%, 10%, 12%, 15%,18%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65% or 70%; a typicalbut non-limited volume fraction of the Mg₂Ni phase is, for example,0.5%, 1%, 1.5%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9% or 10%; a typical butnon-limited volume fraction of the Mg_(x)RE_(y) phase is, for example,0.5%, 1%, 2%, 5%, 8%, 10%, 12%, 15%, 18%, 20% or 22%; and a typical butnon-limited numerical value of x:y is 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1,10:1, 11:1 or 12:1.

The nickel-containing, high-strength and high-toughness, controllablydegradable magnesium alloy material provided in the present disclosuretakes magnesium as a base material, and the Mg₁₂RENi-type long-periodstacking ordered phase and the Mg_(x)RE_(y) phase are formed by addingNi and RE, so that the tensile strength of the alloy material isremarkably improved; meanwhile, a quite large electronegativitydifference exists between the Mg₁₂RENi-type long-period stacking orderedphase and the Mg₂Ni phase, and the magnesium matrix, and a large numberof micro-batteries are formed, so that the generated nickel-containing,high-strength and high-toughness, controllably degradable magnesiumalloy material can be rapidly decomposed, and the downhole fracturingtool made of this magnesium alloy material can effectively meet therequirements of the field of oil and gas exploitation.

Besides, when applied to the field of oil and gas exploitation, thecontrollably degradable alloy material provided in the presentdisclosure can be degraded completely downhole after accomplishing atask, and discharged through a pipe-line, without problems of easyblocking or jam, thus leaving out the drilling and grinding recyclingprocess, reducing the engineering degree of difficulty, and improvingthe construction efficiency.

In one or more embodiments of the present disclosure, when Ni is0.5˜7.5% and RE is 1.5˜19%, in the nickel-containing, high-strength andhigh-toughness, controllably degradable magnesium alloy material; andthe volume fraction of the Mg₁₂RENi-type long-period stacking orderedphase is 4.8˜65%, the volume fraction of the Mg₅RE phase is 1˜15%, andthe volume fraction of the Mg₂Ni phase is 1˜5%, the nickel-containing,high-strength and high-toughness, controllably degradable magnesiumalloy material has the tensile strength of 325˜505 MPa, the yieldstrength of 156˜415 MPa, and the elongation of 6.0˜21.8% at roomtemperature, and the decomposition rate of 363 mm/a˜2500 mm/a in a 3.5wt % KCl solution at 90° C.

In one or more embodiments of the present disclosure, thenickel-containing, high-strength and high-toughness, controllablydegradable magnesium alloy material includes as-cast magnesium alloy,as-extruded magnesium alloy and aged magnesium alloy.

In one or more embodiments of the present disclosure, in the as-castmagnesium alloy, Mg, Ni and RE mainly form an Mg₁₂RENi-type long-periodstacking ordered phase, an Mg₂Ni phase and an Mg₅RE phase, wherein avolume fraction of the Mg₁₂NiRE-type long-period stacking ordered phaseis 3˜65%, a volume fraction of the Mg₂Ni phase is 0.5˜6%, and a volumefraction of the Mg₅RE phase is 0.5˜15%.

In one or more embodiments of the present disclosure, in the as-castmagnesium alloy, a typical but non-limited volume fraction of theMg₁₂NiRE-type long-period stacking ordered phase is, for example, 3%,4%, 5%, 8%, 10%, 12%, 15%, 18%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%,60% or 65%; a typical but non-limited volume fraction of the Mg₂Ni phaseis, for example, 0.5%, 0.8%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%,5.5% or 6%; and a typical but non-limited volume fraction of the Mg₅REphase is, for example, 0.5%, 0.8%, 1%, 2%, 5%, 8%, 10%, 12% or 15%.

In one or more embodiments of the present disclosure, in the as-extrudedmagnesium alloy, Mg, Ni and RE mainly form an Mg₁₂RENi-type long-periodstacking ordered phase, an Mg₂Ni phase and an Mg₅RE phase, wherein avolume fraction of the Mg₁₂NiRE-type long-period stacking ordered phaseis 4˜70%, a volume fraction of the Mg₂Ni phase is 1%˜8%, and a volumefraction of the Mg₅RE phase is 1˜20%.

In one or more embodiments of the present disclosure, in the as-extrudedmagnesium alloy, a typical but non-limited volume fraction of theMg₁₂NiRE-type long-period stacking ordered phase is, for example, 4%,5%, 8%, 10%, 12%, 15%, 18%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%,65% or 70%; a typical but non-limited volume fraction of the Mg₂Ni phaseis, for example, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%,6.5%, 7%, 7.5% or 8%; and a typical but non-limited volume fraction ofthe Mg₅RE phase is, for example, 1%, 2%, 5%, 8%, 10%, 12%, 15%, 18% or20%.

In one or more embodiments of the present disclosure, in the agedmagnesium alloy, Mg, Ni and RE mainly form an Mg₁₂RENi-type long-periodstacking ordered phase, an Mg₂Ni phase and Mg_(x)RE_(y) phase(x:y=(3˜12):1), wherein a volume fraction of the Mg₁₂NiRE-typelong-period stacking ordered phase is 4˜70%, a volume fraction of theMg₂Ni phase is 2%˜10%, and a volume fraction of the Mg₅RE phase is2˜22%.

In one or more embodiments of the present disclosure, in the agedmagnesium alloy, a typical but non-limited volume fraction of theMg₁₂NiRE-type long-period stacking ordered phase is, for example, 4%,5%, 8%, 10%, 12%, 15%, 18%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%,65% or 70%; a typical but non-limited volume fraction of the Mg₂Ni phaseis, for example, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%,7.5%, 8%, 9% or 10%; a typical but non-limited volume fraction of theMg_(x)RE_(y) phase is, for example, 2%, 5%, 8%, 10%, 12%, 15%, 18%, 20%or 22%, wherein a typical but non-limited numerical value of x:y is, forexample, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, 11:1 or 12:1.

In one or more embodiments of the present disclosure, RE is one or moreselected from the group consisting of Gd, Y, Er, Dy, Ce and Sc.

In one or more embodiments of the present disclosure, thenickel-containing, high-strength and high-toughness, controllablydegradable magnesium alloy material includes following components inpercentage by mass: 0.3˜8.5% of Ni, 0.5˜28% of RE, 0.03˜10% of M, andthe balance of Mg and unavoidable impurities, wherein M is an elementcapable of alloying with magnesium.

In one or more embodiments of the present disclosure, in thenickel-containing, high-strength and high-toughness, controllablydegradable magnesium alloy material, a typical but non-limitedpercentage by mass of Ni is, for example, 0.3%, 0.5%, 0.8%, 1%, 1.2%,1.5%, 1.8%, 2%, 2.2%, 2.5%, 2.8%, 3%, 3.2%, 3.5%, 4%, 4.2%, 4.5%, 4.8%,5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8% or 8.5%; a typical but non-limitedpercentage by mass of RE is, for example, 0.5%, 1%, 2%, 3%, 4%, 5%, 8%,10%, 12%, 15%, 18%, 20%, 22%, 25% or 28%; and a typical but non-limitedpercentage by mass of M is, for example, 0.03%, 0.05%, 0.08%, 0.1%,0.15%, 0.2%, 0.5%, 0.8%, 1%, 1.5%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9% or10%.

In one or more embodiments of the present disclosure, M includes, but isnot limited to at least one of Fe, Cu and Mn.

According to a second aspect of the present disclosure, the presentdisclosure provides a method for preparing the above nickel-containing,high-strength and high-toughness, controllably degradable magnesiumalloy material, including the following step:

uniformly mixing a nickel source, a magnesium source and a rare earthsource, and carrying out alloying treatment to obtain thenickel-containing, high-strength and high-toughness, controllablydegradable magnesium alloy material.

The method for preparing a nickel-containing, high-strength andhigh-toughness, controllably degradable magnesium alloy materialprovided in the present disclosure is simple in process and convenientin operation, facilitates large-scale industrial production, and reducesthe cost.

In one or more embodiments of the present disclosure, the alloyingtreatment includes a smelting and casting method and a powder alloyingmethod.

In one or more embodiments of the present disclosure, the nickel sourceis selected from elemental nickel and/or nickel alloy.

In one or more embodiments of the present disclosure, the nickel alloyis one or more selected from the group consisting of magnesium-nickelalloy, nickel-yttrium alloy and zinc-nickel alloy.

In one or more embodiments of the present disclosure, the magnesiumsource is selected from elemental magnesium and/or magnesium alloy.

In one or more embodiments of the present disclosure, the magnesiumalloy is one or more selected from the group consisting ofmagnesium-gadolinium alloy, magnesium-yttrium alloy, magnesium-zincalloy, magnesium-nickel alloy, magnesium-calcium alloy andmagnesium-iron alloy.

In one or more embodiments of the present disclosure, the rare earthsource includes elemental rare earth and/or rare earth intermediatealloy.

In one or more embodiments of the present disclosure, the elemental rareearth includes one or more selected from the group consisting ofgadolinium, yttrium, erbium, dysprosium, cerium and scandium.

In one or more embodiments of the present disclosure, the rare earthintermediate alloy includes at least one selected from the groupconsisting of magnesium-gadolinium alloy, magnesium-yttrium alloy,magnesium-erbium alloy, magnesium-cerium alloy, magnesium-scandiumalloy, nickel-yttrium alloy, nickel-gadolinium alloy, nickel-erbiumalloy, nickel-cerium alloy and nickel-scandium alloy.

In one or more embodiments of the present disclosure, the alloyingtreatment is carried out by adopting the smelting and casting method,including following steps:

(a) casting: uniformly mixing a nickel source, a magnesium source and arare earth source, and carrying out smelting and casting to obtain amagnesium alloy ingot; and

(b) heat treatment: carrying out, in sequence, homogenization treatmentand extrusion heat deformation treatment on the magnesium alloy ingot toobtain the nickel-containing, high-strength and high-toughness,controllably degradable magnesium alloy material.

In the method for preparing a nickel-containing, high-strength andhigh-toughness, controllably degradable magnesium alloy materialprovided in the present disclosure, by carrying out casting and heattreatment in sequence, Mg, Ni and RE in the prepared alloy material formthe Mg₁₂NiRE-type long-period stacking ordered phase, the Mg_(x)RE_(y)phase and the Mg₂Ni phase, not only the tensile strength and plasticityof the alloy material are remarkably improved, but also a large numberof micro-batteries are formed in the alloy material, so that thegenerated nickel-containing, high-strength and high-toughness,controllably degradable magnesium alloy material can be rapidlydecomposed, and a downhole fracturing tool made of this magnesium alloymaterial can be completely degraded downhole, so that the engineeringdifficulty is reduced, and the construction efficiency is improved.

In one or more embodiments of the present disclosure, the step (b) alsoincludes an aging heat treatment step, which is carried out after theextrusion heat deformation treatment, wherein the comprehensiveperformance of the nickel-containing, high-strength and high-toughness,alloy material is more excellent by carrying out the aging heattreatment step.

In one or more embodiments of the present disclosure, in the step (a),when the smelting and casting is carried out, the temperature is firstincreased to 690˜800° C. and maintained, the raw materials are stirredto enable them to melt completely, then the temperature is reduced to630˜680° C. and maintained for 20˜120 min, and after cooling, themagnesium alloy ingot is obtained.

In one or more typical but non-limited embodiments of the presentdisclosure, in the step (a), the temperature after the smelting is, forexample, 690, 700, 710, 720, 730, 740, 750, 760, 770, 780, 790 or 800°C.

In one or more embodiments of the present disclosure, during smeltingand casting, after all the raw materials melt, a typical but non-limitedtemperature after temperature reduction is, for example, 630, 635, 640,645, 650, 655, 660, 665, 670, 675 or 680° C.; and the temperature iskept for, for example, 20, 25, 30, 35, 40, 45, 50, 60, 70, 80, 90, 100,110 or 120 min after temperature reduction.

In one or more embodiments of the present disclosure, the smelting iscarried out using a resistance furnace or a line frequency inductionfurnace.

In one or more embodiments of the present disclosure, at least onecooling method of brine bath, water bath, water quenching or air coolingis used for cooling.

In one or more embodiments of the present disclosure, in the step (a),the nickel source, the rare earth source and the magnesium source areaccurately weighed according to formula requirements, and uniformlymixed.

In one or more embodiments of the present disclosure, the inert gas isused during smelting and casting for protection, wherein the inert gasincludes, but is not limited to, helium, argon, carbon dioxide andsulfur hexafluoride, for example, argon.

In one or more embodiments of the present disclosure, in the step (b),the homogenization treatment is carried out at a temperature of 400˜550°C. for 4˜40 h.

In one or more typical but non-limited embodiments of the presentdisclosure, the homogenization treatment is carried out, for example, ata temperature of 400, 410, 420, 430, 440, 450, 460, 470, 480, 490, 500,510, 520, 530, 540 or 550° C.; and the homogenization treatment iscarried out, for example, for 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15,20, 25, 30, 35 or 40 h.

In one or more embodiments of the present disclosure, the extrusion heatdeformation treatment is carried out at an extrusion ratio of 8˜40.

In one or more typical but non-limited embodiments of the presentdisclosure, the extrusion ratio is, for example, 8, 9, 10, 11, 12, 13,14, 15, 16, 17, 18, 20, 22, 24, 25, 26, 27, 28, 30, 32, 35, 38 or 40.

In one or more embodiments of the present disclosure, the extrusion heatdeformation treatment is carried out at a temperature of 360˜480° C.

In one or more typical but non-limited embodiments of the presentdisclosure, the extrusion heat deformation treatment is carried out at,for example, a temperature of 360, 370, 380, 390, 400, 410, 420, 430,440, 450, 460, 470 or 480° C.

In one or more embodiments of the present disclosure, in the step (b),the aging heat treatment is carried out at a temperature of 150˜250° C.for 12˜120 h.

In one or more typical but non-limited embodiments of the presentdisclosure, the aging heat treatment is carried out at, for example, atemperature of 150, 155, 160, 165, 170, 175, 180, 185, 190, 195, 200,205, 210, 215, 220, 230, 240 or 250° C.; and the aging heat treatment iscarried out, for example, for 12, 13, 14, 15, 16, 17, 18, 19, 20, 22,25, 28, 30, 35, 40, 45, 50, 55, 60, 70, 80, 90, 100, 110 or 120 h.

According to a third aspect of the present disclosure, the presentdisclosure provides use of the above nickel-containing, high-strengthand high-toughness, controllably degradable magnesium alloy material inthe field of oil and gas exploitation.

The technical solutions provided in the present disclosure are furtherdescribed below in connection with embodiments and comparison examples.

Example 1

The present example provides a nickel-containing, high-strength andhigh-toughness, controllably degradable magnesium alloy material,including following components in percentage by mass: 6.9% of Ni, 18% ofY, and the balance of Mg and unavoidable impurities, wherein Mg, Ni andY form an Mg₁₂YNi-type long-period stacking ordered phase, an Mg₅Y phaseand an Mg₂Ni phase, a volume fraction of the Mg₁₂YNi-type long-periodstacking ordered phase is 66%, a volume fraction of the Mg₅Y phase is4%, and a volume fraction of the Mg₂Ni phase is 2%.

A method for preparing a nickel-containing, high-strength andhigh-toughness, controllably degradable magnesium alloy materialprovided in the present example includes following steps:

(1) accurately blending materials according to formula amounts, whereina nickel source, a yttrium source and a magnesium source are added informs of magnesium-yttrium alloy and nickel-yttrium alloy, respectively;

(2) casting: smelting using a resistance furnace or a line frequencyinduction furnace, wherein argon is used as a protective gas in thesmelting process, increasing the temperature to 770° C. and maintainingthe temperature, stirring the raw materials by electromagnetic inductionso that components are homogeneous and raw materials melt fully,reducing the temperature to 655° C. after the raw materials meltcompletely, standing and maintaining the temperature for 25 min, takingout the molten materials to undergo salt bath water cooling to obtain analloy ingot; and

(3) heat treatment: carrying out homogenization treatment, extrusionheat deformation treatment and aging heat treatment on the magnesiumalloy ingot in sequence, and air-cooling the magnesium alloy ingot toroom temperature to obtain the nickel-containing, high-strength andhigh-toughness, controllably degradable magnesium alloy material,wherein the homogenization treatment is carried out at a temperature of500° C. for 10 h; and the extrusion deformation is carried out at atemperature of 400° C., and an extrusion ratio is 11.

Example 2

The present example provides a nickel-containing, high-strength andhigh-toughness, controllably degradable magnesium alloy material,including following components in percentage by mass: 2.3% of Ni, 5.3%of Y, and the balance of Mg and unavoidable impurities, wherein Mg, Niand Y form an Mg₁₂YNi-type long-period stacking ordered phase, an Mg₅Yphase and an Mg₂Ni phase, a volume fraction of the Mg₁₂YNi-typelong-period stacking ordered phase is 23%, a volume fraction of the Mg₅Yphase is 6%, and a volume fraction of the Mg₂Ni phase is 1.8%.

A method for preparing a degradable magnesium alloy material provided inthe present example is the same as that of Example 1, and unnecessarydetails will not be given herein.

Example 3

The present example provides a nickel-containing, high-strength andhigh-toughness, controllably degradable magnesium alloy material,including following components in percentage by mass: 8.5% of Gd, 4.5%of Y, 0.5% of Ni, 0.8% of Mn, and the balance of Mg and unavoidableimpurities, wherein Mg, Gd, Y and Ni form an Mg₁₂YNi-type long-periodstacking ordered phase, an Mg₁₂GdNi-type long-period stacking orderedphase, an Mg₅Gd phase, an Mg₅Y phase and an Mg₂Ni phase, and wherein avolume fraction of the two long-period stacking ordered phases is 15%, avolume fraction of the Mg₅Gd phase and the Mg₅Y phase is 12%, and avolume fraction of the Mg₂Ni phase is 1.2%.

A method for preparing a degradable magnesium alloy material provided inthe present example is different from the preparation method provided inExample 1 in that the homogenization treatment is carried out at atemperature of 540° C. for 4 h; the extrusion deformation is carried outat a temperature of 450° C., and an extrusion ratio is 11; and the agingheat treatment is carried out at a temperature of 200° C. for 50 h. Allof other steps are the same as those in the preparation method inExample 1, and unnecessary details will not be given herein.

Example 4

The present example provides a nickel-containing, high-strength andhigh-toughness, controllably degradable magnesium alloy material,including following components in percentage by mass: 4% of Gd, 4% ofEr, 0.8% of Ni, and the balance of Mg and unavoidable impurities,wherein Mg, Gd, Er and Ni form an Mg₁₂GdNi-type long-period stackingordered phase, an Mg₁₂ErNi-type long-period stacking ordered phase, anMg₅Gd phase, an Mg₅Er phase and an Mg₂Ni phase, and wherein a volumefraction of the two long-period stacking ordered phases is 10.5%, avolume fraction of the Mg₅Gd phase and the Mg₅Er phase is 8%, and avolume fraction of the Mg₂Ni phase is 1.2%.

A method for preparing a degradable magnesium alloy material provided inthe present example is different from the preparation method provided inExample 1 in that the homogenization treatment is carried out at atemperature of 450° C. for 12 h; and the extrusion deformation iscarried out at a temperature of 450° C., and an extrusion ratio is 28.All of other steps are the same as those in the preparation method inExample 1, and unnecessary details will not be given herein.

Example 5

The present example provides a nickel-containing, high-strength andhigh-toughness, controllably degradable magnesium alloy material,including following components in percentage by mass: 19% of Dy, 2.9% ofNi, and the balance of Mg and unavoidable impurities, wherein Mg, Ni andDy form an Mg₁₂DyNi-type long-period stacking ordered phase, an Mg₅Dyphase and an Mg₂Ni phase, and wherein a volume fraction of theMg₁₂DyNi-type long-period stacking ordered phase is 24%, a volumefraction of the Mg₅Dy phase is 11%, and a volume fraction of the Mg₂Niphase is 1.5%.

A method for preparing a degradable magnesium alloy material provided inthe present example is different from the preparation method provided inExample 1 in that the homogenization treatment is carried out at atemperature of 540° C. for 6 h; the extrusion deformation is carried outat a temperature of 360° C., and an extrusion ratio is 28; and the agingheat treatment is carried out at a temperature of 200° C. for 60 h. Allof other steps are the same as those in the preparation method inExample 1, and unnecessary details will not be given herein.

Example 6

The present example provides a nickel-containing, high-strength andhigh-toughness, controllably degradable magnesium alloy material,including following components in percentage by mass: 1% of Ce, 0.5% ofZr, 1% of Ni, and the balance of Mg and unavoidable impurities, whereinMg, Ni, Ce and Zr form an Mg₁₂CeNi-type long-period stacking orderedphase, an Mg₁₂ZrNi-type long-period stacking ordered phase, an Mg₅Zrphase, an Mg₅Ce phase and an Mg₂Ni phase, and wherein a volume fractionof the long-period stacking ordered phases is 4.8%, a volume fraction ofthe Mg₅Zr phase and the Mg₅Ce phase is 2%, and a volume fraction of theMg₂Ni phase is 4%.

A method for preparing a degradable magnesium alloy material provided inthe present example is the same as the preparation method provided inExample 4, and unnecessary details will not be given herein.

Example 7

The present example provides a nickel-containing, high-strength andhigh-toughness, controllably degradable magnesium alloy material,including following components in percentage by mass: 6% of Er, 7.5% ofNi, and the balance of Mg and unavoidable impurities, wherein Mg, Er andNi form an Mg₁₂ErNi-type long-period stacking ordered phase, an Mg₅Erphase and an Mg₂Ni phase, and wherein a volume fraction of theMg₁₂ErNi-type long-period stacking ordered phase is 65%, a volumefraction of the Mg₅Er phase is 3%, and a volume fraction of the Mg₂Niphase is 5%.

A method for preparing a degradable magnesium alloy material provided inthe present example is different from the preparation method provided inExample 1 in that the homogenization treatment is carried out at atemperature of 500° C. for 10 h; and the extrusion deformation iscarried out at a temperature of 400° C., and an extrusion ratio is 11.All of other steps are the same as those in the preparation method inExample 1, and unnecessary details will not be given herein.

Example 8

The present example provides a controllably degradable magnesium alloymaterial, including following components in percentage by mass: 8.0% ofGd, 5.0% of Y, 1.5% of Ni, 0.8% of Mn, and the balance of Mg andunavoidable impurities, wherein Mg, Gd, Y and Ni form Mg₁₂GdNi type andMg₁₂GdY-type long-period stacking ordered phases and Mg₂₄Y₅ and Mg₅Gdphases, and wherein a volume fraction of the Mg₁₂GdNi-type andMg₁₂GdY-type long-period stacking ordered phases is 20%, a volumefraction of the Mg₂₄Y₅ and Mg₅Gd phases is 12%, and a volume fraction ofthe Mg₂Ni phase is 2%.

A method for preparing the degradable magnesium alloy material providedin the present example is different from the preparation method providedin Example 1 in that the homogenization treatment is carried out at atemperature of 540° C. for 4 h; the extrusion deformation is carried outat a temperature of 400° C., and an extrusion ratio is 11; and the agingheat treatment is carried out at a temperature of 200° C. for 50 h. Allof other steps are the same as those in the preparation method inExample 1, and unnecessary details will not be given herein.

In the above Examples 1-8, contents of the unavoidable impurities in themagnesium alloy material are all less than 0.2%.

Comparative Example 1

The present comparative example provides a magnesium alloy material,which is different from Example 1 in that no Ni is contained, and thatthe magnesium-yttrium alloy is prepared according to a conventionalmethod.

Comparative Example 2

The present comparative example provides a magnesium alloy material,which is different from Example 1 in that no Y is contained, and thatthe magnesium-nickel alloy is prepared according to a conventionalmethod.

Comparative Example 3

The present comparative example provides a magnesium alloy material,which is different from Example 1 in that Ni is 0.1% in percentage bymass. A method for preparing the magnesium alloy material is the same asthat in Example 1, and unnecessary details will not be given herein.

Comparative Example 4

The present comparative example provides a magnesium alloy material,which is different from Example 1 in that Ni is 10% in percentage bymass. A method for preparing the magnesium alloy material is the same asthat in Example 1, and unnecessary details will not be given herein.

Comparative Example 5

The present comparative example provides a magnesium alloy material,which is different from Example 1 in that Y is 0.1% in percentage bymass. A method for preparing the magnesium alloy material is the same asthat in Example 1, and unnecessary details will not be given herein.

Comparative Example 6

The present comparative example provides a magnesium alloy material,which is different from Example 1 in that Y is 25% in percentage bymass. A method for preparing the magnesium alloy material is the same asthat in Example 1, and unnecessary details will not be given herein.

Test Example 1

The magnesium alloy materials provided in Examples 1˜7 are respectivelymeasured for tensile strength, yield strength, elongation and corrosionrate, wherein the tensile strength, the yield strength and theelongation are measured at room temperature, a test direction of thetensile strength is an extrusion direction (0°), a tensile speed is 2mm/min, and a corrosion rate is measured at 90° C. in a 3.5 wt % KClsolution. Results are shown in Table 1.

TABLE 1 Table of Property Data of Magnesium Alloy Materials TensileYield Corrosion Strength Strength Elongation Rate Group (MPa) (MPa) (%)(mm/a) Example 1 445 345 11.3 1800 Example 2 404 313 8.9 834 Example 3402 298 10.8 407 Example 4 409 187 20.1 635 Example 5 325 156 21.8 785Example 6 267 185 21 363 Example 7 355 282 17 2100 Example 8 505 415 6.01300 Comparative 410 315 2 10 Example 1 Comparative 140 72 5 2000Example 2 Comparative 425 320 3.5 98 Example 3 Comparative 405 290 —1900 Example 4 Comparative 168 85 5.3 1850 Example 5 Comparative 460 360— 1300 Example 6 Notes: “—” indicates that the material is brittle,which has an extremely low elongation and cannot be put into use.

It can be seen from Table 1 that the nickel-containing, high-strengthand high-toughness, controllably degradable magnesium alloy materialsprovided in Examples 1˜7 have the tensile strength of 267˜505 MPa, theyield strength of 156˜415 MPa, and the elongation of 6.0˜21.8% at roomtemperature, and has the decomposition rate of 363 mm/a 2100 mm/a in a3.5 wt % KCl solution at 90° C., which indicates that the magnesiumalloy material provided in the present disclosure has remarkablyimproved mechanical properties by adding specific contents of nickel andrare earth element to magnesium acting as a base material, and thedegradation rate of the magnesium alloy material can meet the userequirement of self-ablation of downhole tools in the field of petroleumand natural gas.

Finally, it should be noted that the various embodiments above aremerely used for illustrating the technical solutions of the presentdisclosure, rather than limiting the present disclosure; although thedetailed description is made to the present disclosure with reference tovarious preceding embodiments, those ordinarily skilled in the artshould understand that they still could modify the technical solutionsrecited in various preceding embodiments, or make equivalentsubstitutions to some or all of the technical features therein; andthese modifications or substitutions do not make the correspondingtechnical solutions essentially depart from the scope of the technicalsolutions of various embodiments of the present disclosure.

INDUSTRIAL APPLICABILITY

The method for preparing a nickel-containing, high-strength andhigh-toughness, controllably degradable magnesium alloy materialprovided in the present disclosure can be carried out in batch inindustry and is simple in process, convenient in operation, facilitateslarge-scale industrial production, and reduces the production cost, thenickel-containing, high-strength and high-toughness, controllablydegradable magnesium alloy material prepared with this method hasremarkably improved tensile strength and plasticity of alloy materialsand other advantages, moreover, the nickel-containing, high-strength andhigh-toughness, controllably degradable magnesium alloy materialprepared with this method can be rapidly decomposed, and the downholefracturing tools made of this magnesium alloy material can effectivelymeet requirements in the field of oil and gas exploitation.

1. A nickel-containing, high-strength and high-toughness, controllablydegradable magnesium alloy material, comprising following components inpercentage by mass: 0.3˜8.5% of Ni, 0.5˜28% of RE, and a balance of Mgand unavoidable impurities, wherein RE is a rare earth element, and Mg,Ni and RE mainly form an Mg₁₂RENi-type long-period stacking orderedphase, an Mg₂Ni phase and an Mg_(x)RE_(y) phase; a volume fraction ofthe Mg₁₂RENi-type long-period stacking ordered phase is 3˜70%, a volumefraction of the Mg₂Ni phase is 0.5˜10%, a volume fraction of theMg_(x)RE_(y) phase is 0.5˜22%, and a value range of x:y is 3:1˜12:1. 2.The nickel-containing, high-strength and high-toughness, controllablydegradable magnesium alloy material according to claim 1, comprisingfollowing components in percentage by mass: 0.5˜8.0% of Ni, 1.5˜20% ofRE, and a balance of Mg and unavoidable impurities.
 3. Thenickel-containing, high-strength and high-toughness, controllablydegradable magnesium alloy material according to claim 1 or 2, whereinthe RE is at least one selected from the group consisting of Gd, Y, Er,Dy, Ce and Sc; preferably, the nickel-containing, high-strength andhigh-toughness, controllably degradable magnesium alloy materialcomprises following components in percentage by mass: 0.3˜8.5% of Ni,0.5˜28% of RE, 0.03˜10% of M, and a balance of Mg and unavoidableimpurities, wherein M is an element capable of alloying with magnesium.4. The nickel-containing, high-strength and high-toughness, controllablydegradable magnesium alloy material according to claim 3, wherein acontent of the unavoidable impurities, in percentage by mass, is nothigher than 0.2% in the magnesium alloy material.
 5. Thenickel-containing, high-strength and high-toughness, controllablydegradable magnesium alloy material according to claim 3, wherein M isat least one selected from the group consisting of Fe, Cu and Mn.
 6. Amethod for preparing the nickel-containing, high-strength andhigh-toughness, controllably degradable magnesium alloy materialaccording to claim 1, comprising a following step: uniformly mixing anickel source, a magnesium source and a rare earth source, and carryingout alloying treatment to obtain the nickel-containing, high-strengthand high-toughness, controllably degradable magnesium alloy material. 7.The method according to claim 6, wherein the nickel source is selectedfrom elemental nickel and nickel alloy; wherein, the nickel alloy is atleast one selected from the group consisting of magnesium-nickel alloy,nickel-yttrium alloy and zinc-nickel alloy; the magnesium source isselected from elemental magnesium and magnesium alloy; the magnesiumalloy is at least one selected from the group consisting ofmagnesium-gadolinium alloy, magnesium-yttrium alloy, magnesium-zincalloy, magnesium-nickel alloy, magnesium-calcium alloy andmagnesium-iron alloy; and the rare earth source comprises elemental rareearth and/or rare earth intermediate alloy; wherein, the elemental rareearth comprises at least one selected from the group consisting ofgadolinium, yttrium, erbium, dysprosium, cerium and scandium; and therare earth intermediate alloy comprises at least one selected from thegroup consisting of magnesium-gadolinium alloy, magnesium-yttrium alloy,magnesium-erbium alloy, magnesium-cerium alloy, magnesium-scandiumalloy, nickel-yttrium alloy, nickel-gadolinium alloy, nickel-erbiumalloy, nickel-cerium alloy and nickel-scandium alloy.
 8. The methodaccording to claim 6, wherein the alloying treatment comprises asmelting and casting method and a powder alloying method; wherein, thealloying treatment is carried out by the smelting and casting method,wherein, the smelting and casting method comprises following steps: (a)casting: uniformly mixing a nickel source, a magnesium source and a rareearth source, and carrying out smelting and casting to obtain amagnesium alloy ingot; and (b) heat treatment: carrying out, insequence, a homogenization treatment and an extrusion heat deformationtreatment on the magnesium alloy ingot to obtain the nickel-containing,high-strength and high-toughness, controllably degradable magnesiumalloy material; and wherein, the step (b) also comprises an aging heattreatment step, wherein the aging heat treatment step is carried outafter the extrusion heat deformation treatment.
 9. The method accordingto claim 8, wherein in the step (a), when the smelting and casting iscarried out, temperature is first increased to 690˜800° C. andmaintained, raw materials are stirred to enable them to melt completely,then the temperature is reduced to 630˜680° C. and maintained for 20˜120min, and after cooling, the magnesium alloy ingot is obtained, wherein,an inert gas is used during the smelting and casting for protection; anda cooling method is at least one selected from the group consisting ofbrine bath, water quenching, furnace cooling and air cooling.
 10. Themethod according to claim 9, wherein the inert gas is at least oneselected from the group consisting of helium, argon, carbon dioxide andsulfur hexafluoride.
 11. The method according to claim 9, wherein theinert gas is argon.
 12. The method according to claim 9, wherein thesmelting is carried out using a resistance furnace or a line frequencyinduction furnace.
 13. The method according to claim 6, wherein, in thestep (b), the homogenization treatment is carried out at a temperatureof 400˜550° C. for 4˜40 h; and in the step (b), the extrusion heatdeformation treatment is carried out at an extrusion ratio of 8˜40; andpreferably, the extrusion heat deformation treatment is carried out at atemperature of 360˜480° C.
 14. The method according to claim 6, whereinthe aging heat treatment is carried out at a temperature of 150˜250° C.for 12˜120 h.
 15. The method according to claim 6, wherein the agingheat treatment is carried out at a temperature of 180˜220° C. for 15˜60h.
 16. Use of the nickel-containing, high-strength and high-toughness,controllably degradable magnesium alloy material according to claim 1 ina field of oil and gas exploitation.
 17. The nickel-containing,high-strength and high-toughness, controllably degradable magnesiumalloy material according to claim 2, wherein the nickel-containing,high-strength and high-toughness, controllably degradable magnesiumalloy material comprises an as-cast magnesium alloy, an as-extrudedmagnesium alloy and an aged magnesium alloy.
 18. The nickel-containing,high-strength and high-toughness, controllably degradable magnesiumalloy material according to claim 17, wherein the as-cast magnesiumalloy comprises an Mg₁₂RENi-type long-period stacking ordered phase, anMg₅RE phase and an Mg₂Ni phase, wherein a volume fraction of theMg₁₂RENi-type long-period stacking ordered phase is 3˜65%, a volumefraction of the Mg₂Ni phase is 0.5˜6%, and a volume fraction of theMg₅RE phase is 0.5˜15%.
 19. The nickel-containing, high-strength andhigh-toughness, controllably degradable magnesium alloy materialaccording to claim 17, wherein the as-extruded magnesium alloy comprisesan Mg₁₂RENi-type long-period stacking ordered phase, an Mg₂Ni phase andan Mg₅RE phase, wherein a volume fraction of the Mg₁₂RENi-typelong-period stacking ordered phase is 4˜70%, a volume fraction of theMg₂Ni phase is 1%˜8%, and a volume fraction of the Mg₅RE phase is 1˜20%.20. The nickel-containing, high-strength and high-toughness,controllably degradable magnesium alloy material according to claim 17,wherein the aged magnesium alloy comprises an Mg₁₂RENi-type long-periodstacking ordered phase, an Mg₂Ni phase and an Mg_(x)RE_(y) phase,wherein a volume fraction of the Mg₁₂RENi-type long-period stackingordered phase is 4˜70%, a volume fraction of the Mg₂Ni phase is 2˜10%,and a volume fraction of the Mg_(x)RE_(y) phase is 2˜22%, wherein avalue range of x:y is 3:1˜12:1.